In the use of such as adhesives, external paints (coating materials), a hard coat, and an anti-reflection film (membrane), various studies have been made to improve scratch resistance, mechanical strength of the hardened materials, adherence of a certain material with other materials it contacts, and the like, by means of blending an organic material and an inorganic material. In particular, in the combination of an inorganic material and a polymerization-curing organic material, an alkoxysilane having a polymerizing group, and/or a hydrolyzed condensation product thereof, attracts attention in the arts. For example, JP-A-9-169847 (“JP-A” means unexamined published Japanese patent application) proposes a combination of a particular polyalkoxypolysiloxane and a polymerizing silane-coupling agent. However, the scratch resistance and the mechanical strength of the thus-obtained hardened materials are unsatisfactory, because the polyalkoxy polysiloxane and the polymerizing silane-coupling agent do not react well, and the resultant introduction rate of the polymerizing group is low. JP-A-9-40909 reports a partially co-hydrolyzed condensation product of an alkoxysilane having an organic functional group and a tetraalkoxysilane. However, the storage stability of a liquid of the partially co-hydrolyzed condensation product is not satisfactory.
In a display device such as a cathode ray tube display device (CRT), a plasma display (PDP), an electroluminescence display (ELD) or a liquid crystal display device (LCD), an anti-reflection film is generally arranged on the outermost face of the display device to decrease the reflectivity through the principle of optical interference to prevent a drop in the contrast based on the reflection of external light or prevent reflection of undesired images in its screen.
Such an anti-reflection film can be produced by forming a high refractive index layer on a support and further forming a low-refractive-index layer having an appropriate thickness thereon. To realize low reflectivity, the low-refractive-index layer is desirably made of a material whose refractive index is as low as possible. High scratch resistance is required for the anti-reflection film, since it is used as the outermost surface of a display. To realize high resistance to scratch (abrasion) in a thin film of about 100 nm in thickness, it is important to enhance both the mechanical strength of the film and the adhesive property to a subbing layer.
To lower the refractive index of material, it is possible to adopt the method (1) of introducing a fluorine atom into the material, or the method (2) of lowering the density of the material (introducing pores into the material). However, with both of the methods, a tendency is generated for the film strength and adhesive property to be damaged and the scratch resistance to deteriorate. Thus, it is difficult to achieve both a low refractive index and high scratch resistance.
For example, JP-A-11-189621, JP-A-11-228631 and JP-A-2000-313709 describe means to improve scratch resistance by introducing a polysiloxane structure into a fluorine-containing polymer thereby reducing the coefficient of friction of the film surface. Though these means are effective for improving scratch resistance to some degree, it is difficult to obtain a satisfactory scratch resistance by a single use of the said means on the occasions that the film lacks essential film strength and interface adhesion property.
One effective means to increase film strength is to introduce an inorganic filler into a low-refractive-index layer. The use of inorganic particles of a low refractive index as a filler enables increasing film strength without increasing the refractive index of the layer itself.
However, it is difficult to improve the adhesion property to the under layer by introducing an inorganic filler, so that satisfactory scratch resistance has not yet been obtained.